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Tuesday, January 16, 2018

A Goliath Comeback

Massive and impassive, the goliath grouper may seem the stereotypical image of a stolid, uncomprehending fish. But appearances are deceiving.

“They’re almost as smart as a dog,” says Dr. Ari Fustukjian, The Florida Aquarium associate veterinarian who cares for the facility’s two goliath groupers, Cleatus and Gill. “Long-lived apex predators can be quite intelligent.”

The goliaths, the Atlantic’s largest grouper, are astute in responding to their environment and conveying their needs. Aquarium biologists regularly perform “enrichment” dives with the fish. These dives are not aimed at training the fish to do tricks, but rather intended to promote behaviors, such as rolling on their side or opening their mouths, that allow veterinary staff to better monitor their health. The interaction also provides the fish with mental and physical stimulation they seem to enjoy.

“We never force the fish to do anything it doesn’t want to do,” says Fustukjian.

Many animals respond to food as reinforcement during enrichment dives. Not the goliaths. Fustukjian says they like tactile sensations, such as having sand poured over their backs or air bubbles blown on them. They will roll on their sides or open their mouths to enjoy the feel of the bubbles. This allows Fustukjian to see all the way to the back of the fish’s mouth. During these enrichment dives, Fustukjian stresses, the fish are never deprived of anything to promote a certain behavior. Rather, the divers respond to what the fish indicate they like. For instance, Aquarium biologists made a mop of car wash fabric to rub the fish. The goliaths love the sensation, and the fabric doesn’t disturb the fish’s delicate slime coating essential to its welfare.

The goliaths often readily respond to the divers and even have “favorite” keepers. Goliaths are highly territorial, and the two at The Florida Aquarium are kept in separate habitats.

Cleatus, who is about five-and-and-a-half feet long and 300 pounds, lives in the Bays and Beaches gallery. Gill, about four-and-a-half feet long and 200 pounds, lives in the main coral reef habitat. Officials are not sure about their ages. Cleatus came to Aquarium in 1995, already a large fish.

Fustukjian says when protecting its space, a goliath will open its gills and slam them shut, making a booming sound that can be “felt through the clear acrylic viewing window.” Offshore divers report it can feel like the shock waves from an underwater explosion. Goliaths grow to 800 pounds and are exceptionally long lived. Fustukjian says a 37-year-old goliath has been documented, but some believe they may live 50 years or more.

They spend their early years in mangroves, which are so essential to Florida’s marine life. The Florida Museum of Natural History estimates 75 percent of game fish and 90 percent of commercial species in South Florida depend on mangroves for at least part of their life cycles. Goliaths become sexually mature in about five or six years, and the larger fish move to deeper water, but not necessarily far offshore. There are many around the Sunshine Skyway Bridge. As a kid, I remember being part of a crowd that gathered around the Big Indian Rocks pier as a man pulled a 300-pound goliath (then insensitively called Jewfish) ashore. He had hooked it with a huge hook and rope, and it was amazing to think such a giant swam so close to the beach. It retrospect, it was not the most sporting way to catch the fish.

It is no surprise the slow-to-mature goliath was fished almost to extinction, resulting in a 1990 fishing ban for both state and federal waters. The fish’s numbers have since rebounded, and now some fishermen complain the goliaths are eating their catch before they can be reeled to the boat. Some anglers claim the giant groupers are hurting reef-fish populations, though studies show goliaths eat mostly crabs. The goliaths are unquestionably efficient predators, so large they can simply “inhale” their prey.

The Aquarium’s goliaths are fed a mixture of fish and vitamins, with the amounts carefully calculated. Still, Cleatus and Gill occasionally will slurp down a fellow resident in their habitat, which Fustukjian says signals the need to increase food portions.

Florida officials are considering a limited season for goliath groupers. Fustukjian is glad regulations saved the fish from extinction. But says exceptional care must be taken. He explained, “When you have a long-lived fish, it can be hard to tell how the whole population is going. You may have a lot of adults, but if your juvenile population isn’t healthy, you may not see repercussions for a long time.”

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